IOO 
F. W. Oliver. 
strands of tracheal elements. The tracheal sheath in this seed 
consequently differs from that obtaining in Stephanospermum on the 
one hand, where the tracheal mantle is continuous, and from forms 
like Aetlieotesta on the other where the strands would appear to 
run quite independent of one another in a longitudinal direction 1 
Polylophospermum stepliancnse , Brongniart, 2 is a long prismatic 
seed, hexagonal in transverse section and prominently ribbed along 
the salient angles. Each prismatic face also bears a low median, 
secondary ridge, whilst the space between the ridges is occupied by 
a softer tissue. 
The seed is some 15 mm. in length, and in addition to the long 
micropylar beak, the testa expands at the apex and base into 
cupular emergences in such a way as to produce a sort of false 
chamber at either end of the seed. These chambers enclose 
respectively the micropylar beak and the pedicel or funicle. The 
nucellus bears a large distal pollen-chamber, whilst the remains of 
the prothallium form a vesicle usually open above. 
In general our specimens correspond with Brongniart’s sketch. 3 
Photo 5 shews the seed in fairly median longitudinal section with 
the micropylar aperture at the summit (M). Around it, as at the 
chalaza also, are shewn the characteristic ensheathing outgrowths 
or expansions of the testa which form so peculiar a feature in this 
seed. The internal portions of the seed are contracted away from 
the testa and include (1) a delicate layer ( E) probably the remains 
of the lining of the testa, (2) the nucellus of which the broad, flat- 
roofed upper portion is the pollen-chamber (PC.), whilst the lower 
tubular body contains the remains of a prothallium here represented 
by a cellular vesicle open above (0), in which feature it precisely 
recalls Brongniart’s figure. In view of the state of preservation of 
both the specimens no data are available throwing light on the 
relations of testa and nucellus. 
The section adjacent to that figured traverses the pollen- 
chamber obliquely, whilst lower down it re-enters the body of the 
nucellus (evidently somewhat displaced) and skims along its wall 
in a tangential direction. A portion of this tangentially cut tissue is 
shown considerably enlarged in photo. 10, with the tracheal strands 
(darker in the photo.) ljing in situ at many places. In both sections 
the external limiting layer or epidermis of the nucellus is still in 
1 B. Renault, Flore fossile d’ Autun, &c., p. 274. 
1 I,r>c. cit., p. 28, pi. C., Fig. 6, 7 and 8. 
3 I,oc. cit., pi. C., fig. C. 
